What are the Halogens in the Periodic Table? - Quora Quora Daniel James Berger , PhD in organic chemistry The elements in Group 17 of the periodic table ( The Old fashioned name for Group 17 is Group VII ) are known collectively as The Halogens. They are the elements Fluorine, ( atomic number 9 ), Chlorine, ( atomic number 17 ), Bromine ( atomic number 35 ), Iodine ( atomic number 53 ), Astatine ( atomic number 85 ), and a newly discovered element not yet given a name, that has an atomic number of 117, ( Discovered in 2010). However both Astatine and Element No. 117 are too radioactive to be made in quantities that can be weighed. They are man made elements that have very short half lives; so decay into other elements before one has the chance to make any of their compounds. So in most laboratories Halogen chemistry is essentially about the study of Fluorine, Chlorine, Bromine & Iodine. The word Halogen was coined in 1842 by the Swedish Chemist Berzelius ( 1779 - 1848 ).

It is a made up Swedish word which literally means "Salt producer" in Swedish. A name in keeping with the reactive nature of these elements. Lots of Halogen salts are known. Eg. Sodium chloride. Potassium fluoride. Sodium Bromide. These elements are all members of the same group, because all of their atoms have the same number of electrons in their outermost shell or orbit. Group 17 elements all have 7 electrons in their outermost orbit. ​ ​The Periodic Table highlighting Group 17. Fluorine As mentioned previously fluorine has an atomic number of 9. This means that an atom of fluorine will have in addition to 9 protons in the nucleus of its atom, it will have a total of 9 electrons orbiting its nucleus. An individual proton always has a charge of +1 and an individual electron always has a charge of -1. We have 9 protons in an atom of fluorine each having a charge of +1, plus 9 electrons in that same atom orbiting the nucleus of that atom. ( +1 X 9 ) + (-1 X 9 ) = 0. So the atom is electrically neutral.

This is true for all neutral atoms of fluorine. The 9 electrons are arranged in 2 shells or orbit. 2 of the 9 electrons orbit in the 1st shell or orbit. The remaining 7 electrons orbit in a larger shell. The 7 electrons in the outermost orbit of all Halogens are the electrons that participate in chemical reactions. During chemical reactions the number of electrons in the outermost orbit can go up or down. Up to a max of 8, and down to 0 ( in theory ). Compare with Na+1 or with Li+1 ​ Written Feb 7, 2016 The halogens are the family of chemical elements that includes fluorine (atomic symbol F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The halogens make up Group VIIA of the Periodic Table of the elements. Elemental halogens are diatomic molecules. However, due to their high reactivity, the halogens are never found in nature in native form. The family name means "salt-forming," from the Greek for salt, "hals", and for generating "genes".

The salinity of the oceans on Earth is due in large part to such halogen salts (halides) as sodium chloride (NaCl) and potassium iodide (KI). Halogens display physical and chemical properties typical of nonmetals. They have relatively low melting and boiling points that increase steadily down the group. Near room temperature, the halogens span all of the physical states: Fluorine and chlorine are gases, bromine is a liquid, and iodine is a solid. All of the elements are colored, with the color becoming more intense moving down the group. Fluorine gas is pale yellow, and chlorine gas is a yellowish green. Liquid bromine and its vapors are brownish red. Solid iodine appears as shiny, dark gray crystals, and the vapors are a deep purple. The halogens are poor thermal and electrical conductors in all phases, and as solids they are brittle and crumbly. The halogens have distinctive, unpleasant odors, will burn exposed flesh, and are toxic. The neutral atoms of the halogens possess seven outer electrons. An additional electron can be added to halogen atoms to form singly charged negative ions. These ions have a closed outer-shell configuration.

Electronegativity is a measure of the ability of an atom of one element to remove an electron from an atom of another element. As a group, the halogens are among the most electronegative elements. Fluorine has the highest electronegativity of all the elements. Halogens are so reactive that all the elements except helium and neon have been found to react with at least one of the halogens. Fluorine is always assigned a formal oxidation number of –1, whereas the other halogens can exhibit a range of oxidation numbers 526 Views · View Upvotes · Answer requested by Properties of the Halogens About Watch and Favorite Watch Watching this resources will notify you when proposed changes or new versions are created so you can keep track of improvements that have been made. Favorite Favoriting this resource allows you to save it in the “My Resources” tab of your account. There, you can easily access this resource later when you’re ready to customize it or assign it to your students. Properties of the Halogens Halogens (fluorine, chlorine, bromine, iodine, astatine) are nonmetal elements that are highly electronegative and reactive.

Learning Objective Describe the physical and chemical properties of halogens. Key Points Halogens are nonmetals in group 17 (or VII) of the periodic table. Down the group, atom size increases. As a diatomic molecule , fluorine has the weakest bond due to repulsion between electrons of the small atoms. Due to increased strength of Van der Waals forces down the group, the boiling points of halogens increase. Therefore, the physical state of the elements down the group changes from gaseous fluorine to solid iodine. Due to their high effective nuclear charge , halogens are highly electronegative . Therefore, they are highly reactive and can gain an electron through reaction with other elements. Halogens can be harmful or lethal to biological organisms in sufficient quantities. Terms Register for FREE to remove ads and unlock more features! Learn more Full Text The halogens are a series of non-metal elements from group 17 of the periodic table (formerly VII). The halogens include fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At). The artificially created element 117 (ununseptium) may also be considered a halogen.

Physical Properties Atoms get bigger down the group as additional electron shells are filled. When fluorine exists as a diatomic molecule, the F–F bond is unexpectedly weak. This is because fluorine atoms are the smallest of the halogens—the atoms are bonded close together, which leads to repulsion between free electrons in the two fluorine atoms. The boiling points of halogens increase down the group due to the increasing strength of Van der Waals forces as the size and relative atomic mass of the atoms increase. This change manifests itself in a change in the phase of the elements from gas (F2, Cl2) to liquid (Br2), to solid (I2). The halogens are the only periodic table group containing elements in all three familiar states of matter (solid, liquid, and gas) at standard temperature and pressure . Halogens represents all of the three familiar states of matter: (left to right) chlorine is a gas, bromine is a liquid, and iodine is a solid. Highly reactive fluorine is not included in the picture. Chemical Properties Electronegativity is the ability of an atom to attract electrons or electron density towards itself within a covalent bond .

Electronegativity depends upon the attraction between the nucleus and bonding electrons in the outer shell. This, in turn, depends on the balance between the number of protons in the nucleus, the distance between the nucleus and bonding electrons, and the shielding effect of inner electrons. In hydrogen halides (HX, where X is the halogen), the H-X bond gets longer as the halogen atoms get larger. This means the shared electrons are further from the halogen nucleus, which increases the shielding of inner electrons. This means electronegativity decreases down the group. Halogens are highly reactive, and they can be harmful or lethal to biological organisms in sufficient quantities. This reactivity is due to high electronegativity and high effective nuclear charge. Halogens can gain an electron by reacting with atoms of other elements. Fluorine is one of the most reactive elements. It reacts with otherwise inert materials such as glass , and it forms compounds with the heavier noble gases . It is a corrosive and highly toxic gas. Fluorine's reactivity means that once it does react with something, it bonds so strongly that the resulting molecule is inert and non-reactive.

Fluorine can react with glass in the presence of small amounts of water to form silicon tetrafluoride (SiF4). Thus fluorine must be handled with substances like the inert organofluorine compound Teflon. Fluorine reacts vigorously with water to produce oxygen (O2) and hydrogen fluoride: $2 F_2 (g) + 2 H_2O (l) \rightarrow O_2 (g) + 4 HF (aq)$ Chlorine has maximum solubility of 7.1 g per kg of water at ambient temperature (21 °C). Dissolved chlorine reacts to form hydrochloric acid (HCl) and hypochlorous acid (HClO), a solution that can be used as a disinfectant or bleach: $Cl_2 (g) + H_2O (l) \rightarrow HCl (aq) + HClO (aq)$ Bromine has a solubility of 3.41 g per 100 g of water.

It slowly reacts to form hydrogen bromide (HBr) and hypobromous acid (HBrO): $Br_2 (g) + H_2O (l) \rightarrow HBr (aq) + HBrO (aq)$ Iodine is minimally soluble in water, with a solubility of 0.03 g per 100 g water. However, iodine will form an aqueous solution in the presence of iodide ion . This occurs with the addition of potassium iodide (KI), forming a triiodide ion. Periodic Table of the Elements - Halogens Electron Configuration Halogens The halogens are located in Group 17 (VIIA) of the periodic table and belongs to a class of nonmetals. The halogen elements are fluorine, chlorine, bromine, iodine, astatine, and ununseptium. Ununseptium is artificially created element. The term "halogen" means "salt-former" and compounds containing halogens are called "salts".

Properties of halogens: The halogens exist in all three states of matter at standard temperature and pressure: Solid- Iodine, Astatine Liquid- Bromine Gas- Fluorine, Chlorine All halogens have 7 valence electrons in their outer shells, giving them an oxidation number of -1. Halogens lack only one electron to form a complete shell. All of the halogens are components of acids. They form diatomic molecules in the pure state. The halogens are also all toxic. Halogens have very high electronegativities. Their electronegativity decreases down group from fluorine to astatine (refer to the table below for supporting data). Halogens are highly reactive, especially with alkali metals and alkaline earths. Halogens are extremely active chemically. Chemical activity increases as you move upward in the group, fluorine being the most active element in the periodic table. Their boiling Point increases down group from fluorine to astatine (refer to the table below for supporting data) Their atomic size increases down group from fluorine to astatine (refer to the table below for supporting data).

Their ionic size increases down group from fluorine to astatine (refer to the table below for supporting data). Interhalogens : Compounds composed of two or more different halogen atoms are called as interhalogens. For ex. Chlorine trifluoride, Iodine heptafluoride Physical and atomic properties of halogens: PTTb.htm 0.228 0.266 As the atomic mass (and the size of the atom) of the Group 7 elements (halogens) increases the: boiling point density all increase. The reason why these halogens are reactive is that they all have one electron missing in their outer shell. This means that the atoms of the halogens are not "very happy" and they will do all they can to gain one more electron such that all the electrons in the outer shells have partners.. In order of reactivity fluorine is the most reactive followed by chlorine, then bromine, iodine and astatine is the least reactive. Electronic configurations.

Astatine - Element information, properties and uses | Periodic Table Chemistry in its element: astatine (Promo) You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry. (End promo) Chris Smith Hello, a record breaker is the star of the show this week as we meet the chemical whose name means unstable and which is in the famous Guinness book as the world's rarest elements, but some bright medical future turn this rarity into something in common use. The element is astatine and to tell the story here is Mark Peplow. Mark Peplow You can learn a lot about someone by meeting their family and the same is true for the element. That's how we come to know so much about astatine. Often trumpeted as the rarest naturally occurring element in the world, it's only by extrapolating the properties of the other members of the halogen family, fluorine, chlorine, bromine and iodine the scientists could even begin to look at their obese sibling.

Astatine was the second synthetic element to be conclusively identified just three years after technetium, was isolated by Carlo Perrier and Emilio Segre of the University of Palermo. The element had actually been created in a cyclotron particle accelerator at the University of California in Berkeley where Segre spent the following summer continuing his research. But miles away from Italy Mussolini's government passed anti Semitic laws which barred Jewish people like Segre from holding University positions; so he stayed where he was, taking up a job at Berkeley and in 1940 he helped to discover astatine along with Dale Corson, he was then a post doc and later went on to become President of Cornell University and grant student Kenneth MacKenzie. They bombarded a sheet of bismuth metal, that's two doors down from astatine in the periodic table, with alpha particle to produce astatine-211, which has a half life of about 71/2 hours and it neatly filled the gap in the periodic table just beneath iodine. Segre went on to become a group leader for the Manhattan project which built the first atomic weapon.

And it was only once the Second World War was over that the trio proposed the name Astatine for their elemental discovery. It was from the Greek word meaning unstable. Astatine is actually found in nature although it only appears as a minor spur on an obscure pathway in uranium fission. According to Greenwood and Earshaw, the Bible of inorganic chemistry, it's been estimated that the top kilometre of the earth's crust contains less than 50 mg of astatine making a Guinness world record's rarest element. Astatine is the least reactive of the halogens but just like the rest of them it combines with hydrogen to make hydrogen astatide which dissolves in water to make hydroastatic acid; it is just like a weaker version of hydrochloric acid. If you could ever isolate enough of this stuff astatine would be an even darker purple solid than iodine. Overall there are more than 30 isotopes of the element, all radioactive with the longest lived having a half life of just 8 hours. You might think that something so rare would be completely useless, but perhaps not. Several groups of scientists believe that astatine-211 could be used to treat certain types of cancer.

Radioactive Iodine 131 is already used to treat Thyroid cancers for example, because it preferentially accumulates in that organ. This concentrates the dose of radiation and it reduces the exposure of healthy tissue. The trouble is that Iodine 131 like many other therapeutic radioisotopes emit beta particles, fast moving electrons which can penetrate through a few millimetres of tissue. That makes them ideal for tackling substantial solid tumours, but not for the small clusters of cells, because the energy from radioactive decay is spread far outside the boundary of the tumour. Another form of radioactive decay, alpha particles would be much more suitable because these bulky clusters of 2 protons and 2 neutrons, effectively helium nucleus, can only travel about 50 micrometers in tissue. Astatine-211 is not only an alpha emitter, it has also got a very short half life and the fact that it decays to a stable non-radioactive isotope of lead means that the radiation dose is quite brief. It even has a secondary decay pathway that creates a few x-rays which doctors could use to track exactly where the isotope is in the body.

The key challenge is though to connect the radioactive astatine atoms to a molecule that will seek out specific cancer cells; then to the chemistry as soon as possible before the radioactivity decays away and to make sure that the astatine doesn't fall off its targeted molecule once it is injected into the body. This may of course take decades of research to achieve but chemists have already identified rapid ways to make these astatine complexes and there has even been a small but very promising clinical trial at Duke University in North Carolina, testing astatine radiotherapy in 18 brain tumour patients. So if astatine does become a successful medicine there's every chance that the rarest element might become surprisingly common. Chris Smith Mark Peplow, telling the tale of the world's rarest element. Well from rare to lethal now and especially if you're a monk. Phillip Ball Valentine admitted that antimony was poisonous. In fact he offered an apocryphal explanation for the name, saying that it derives from anti-monachos, meaning anti-monk in Latin because he once unintentionally poisoned several of his fellow monks by adding it secretly to their food in an attempt to improve their health.

Chris Smith Phil Ball who will be bringing antimony to life for us in next week's Chemistry in its element. I'm Chris Smith, thank you for listening. See you next time. (Promo) Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com . There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements . (End promo) halogen element | Facts, Definition, Properties, & Uses | Britannica.com Halogen element Alternative Titles: Group 17 element, Group VIIa element Related Topics iodine (I) Halogen element, any of the six nonmetallic elements that constitute Group 17 (Group VIIa) of the periodic table. The halogen elements are fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts). They were given the name halogen, from the Greek roots hal- (“salt”) and -gen (“to produce”), because they all produce sodium salts of similar properties, of which sodium chloride—table salt , or halite —is best known. Modern version of the periodic table of the elements.

Encyclopædia Britannica, Inc. Because of their great reactivity, the free halogen elements are not found in nature. In combined form, fluorine is the most abundant of the halogens in Earth’s crust. The percentages of the halogens in the igneous rocks of Earth’s crust are 0.06 fluorine, 0.031 chlorine, 0.00016 bromine, and 0.00003 iodine. Astatine and tennessine do not occur in nature, because they consist of only short-lived radioactive isotopes . The halogen elements show great resemblances to one another in their general chemical behaviour and in the properties of their compounds with other elements. There is, however, a progressive change in properties from fluorine through chlorine, bromine, and iodine to astatine—the difference between two successive elements being most pronounced with fluorine and chlorine. Fluorine is the most reactive of the halogens and, in fact, of all elements, and it has certain other properties that set it apart from the other halogens. Chlorine is the best known of the halogen elements.

The free element is widely used as a water-purification agent, and it is employed in a number of chemical processes. Sodium chloride, of course, is one of the most familiar chemical compounds. Fluorides are known chiefly for their addition to public water supplies to prevent tooth decay , but organic fluorides are also used as refrigerants and lubricants. Iodine is most familiar as an antiseptic , and bromine is used chiefly to prepare bromine compounds that are used in flame retardants and as general pesticides . In the past ethylene dibromide was extensively used as an additive in leaded gasoline . Oxidation cobalt (Co) Probably the most important generalization that can be made about the halogen elements is that they are all oxidizing agents ; i.e., they raise the oxidation state, or oxidation number , of other elements—a property that used to be equated with combination with oxygen but that is now interpreted in terms of transfer of electrons from one atom to another. In oxidizing another element, a halogen is itself reduced; i.e., the oxidation number 0 of the free element is reduced to −1.

The halogens can combine with other elements to form compounds known as halides —namely, fluorides , chlorides , bromides , iodides , and astatides. Many of the halides may be considered to be salts of the respective hydrogen halides , which are colourless gases at room temperature and atmospheric pressure and (except for hydrogen fluoride) form strong acids in aqueous solution. Indeed, the general term salt is derived from rock salt , or table salt (sodium chloride). The tendency of the halogen elements to form saltlike (i.e., highly ionic) compounds increases in the following order: astatine < iodine < bromine < chlorine < fluorine . Fluorides are usually more stable than the corresponding chlorides, bromides, or iodides. (Often astatine is omitted from general discussions of the halogens because less is known about it than about the other elements.) Ionic bond Encyclopædia Britannica, Inc. The oxidizing strength of the halogens increases in the same order—i.e., from astatine to fluorine. Therefore, of the halogen elements, elemental fluorine is prepared with the greatest difficulty and iodine with the least.

As a class, the halogen elements are nonmetals, but astatine shows certain properties resembling those of the metals. Electronic structure Periodic Table of the Elements The chemical behaviour of the halogen elements can be discussed most conveniently in terms of their position in the periodic table of the elements. In the periodic table the halogens make up Group 17 (according to the numbering system adopted by the International Union of Pure and Applied Chemistry), the group immediately preceding the noble gases. The halogen atoms carry seven valence electrons in their outermost electron shell . These seven outermost electrons are in two different kinds of orbitals , designated s (with two electrons) and p (with five). Potentially, a halogen atom could hold one more electron (in a p orbital), which would give the resulting halide ion the same arrangement (configuration) as that of the noble gas next to it in the periodic table. These electron configurations are exceptionally stable. This pronounced tendency of the halogens to acquire an additional electron renders them strong oxidizers. Britannica Stories EU Considers Rules For Robots At room temperature and atmospheric pressure the halogen elements in their free states exist as diatomic molecules .

In molecular fluorine (F2) the atoms are held together by a bond made from the union of a p orbital from each atom, with such a bond being classed as a sigma bond . It should be mentioned that the dissociation energy for fluorine (the energy necessary to break the F−F bond) is over 30 percent smaller than that of chlorine but is similar to that of iodine (I2). The weakness of the F−F single bond compared with chlorine can be ascribed to the small size of fluorine resulting in a decreased overlap of bonding orbitals and an increased repulsion of the nonbonding orbitals. In iodine, however, the p orbitals are more diffuse, which means the bond becomes weaker than in chlorine or bromine. Relative reactivity The great reactivity of fluorine largely stems from the relatively low dissociation energy, a standard measure for bond energies, of the F−F bond (37.7 kilocalories per mole) and its ability to form stable strong bonds with essentially all the other elements. Fluorine (F2) and chlorine (Cl2) are gases at room temperature.

Bromine (Br2) is a reddish-brown liquid at room temperature and is—apart from mercury —the only element that is liquid at 20 °C (68 °F) and atmospheric pressure. Iodine (I2) forms dark violet crystals under these conditions. In the solid state the halogen elements form molecular lattices, and the sublimation energies rise with increasing size of the molecules. Connect with Britannica Facebook Twitter YouTube Instagram Pinterest The energy released in the formation of an ion from a free atom and an electron (brought up from an infinite distance) is called the electron affinity . The electron affinities for the halogen atoms all are high and show only slight differences from one another. It is known, however, that the oxidizing properties (ability to take up an electron by formation of a bond with another atom) increase from astatine to fluorine. This increase can be attributed to the low dissociation energy and the high electron affinity of fluorine combined with the strength of the resulting fluorine-hetero atom bond, resulting in a large heat of reaction. While the fluoride ion exhibits no reducing properties, the iodide ion is a mild reducing agent.

Within a molecule in which atoms are held together by a shared electron pair (i.e., by a covalent or nonionic bond), the tendency of an atom to attract the shared electrons may be expressed by an electronegativity value. According to American chemist Linus Pauling , “Electronegativity is the power of an atom in a molecule to attract electrons to itself.” Fluorine possesses the highest electronegativity of all elements, and there is a decrease in electronegativity within the family of the halogen elements from fluorine through chlorine, bromine, and iodine to astatine. Fluorine replaces any other halide ion from its compounds, as shown in the following equations. Chlorine, however, replaces only bromide, iodide, and astatide ions, and bromine only iodide and astatide ions. Free fluorine, chlorine, bromine, and iodine are expected to replace astatide ions. The halogen elements all form compounds with hydrogen , the hydrogen halides . The energy of the hydrogen-halogen bond increases strongly from iodide to fluoride.

Hydrogen fluoride in the crystalline state consists of infinite zigzag chains, as shown in the diagram, in which H represents the hydrogen atoms and (as before) F the fluorine atoms; the solid lines represent covalent bonds between the hydrogen and fluorine atoms within the molecules, and the dotted lines represent secondary bonds, called hydrogen bonds . The hydrogen bonds between hydrogen fluoride molecules are considerably weaker (7 kilocalories per mole) than those within the molecules (135 kilocalories per mole), yet they are retained to a great extent in the liquid state. Similar hydrogen bonding exists in the other hydrogen halides, but it is considerably weaker. The large difference in hydrogen bonding between hydrogen fluoride and the other hydrogen halides accounts for the relatively high melting and boiling points of hydrogen fluoride as compared with those of hydrogen chloride and the other hydrogen halides. The hydrogen-halogen bond energies also decrease considerably in going from hydrogen fluoride to hydrogen iodide. Britannica Lists & Quizzes Editor Picks: Exploring 10 Types of Basketball Movies The ionization energies of the halogens are generally high, but they fall markedly with increasing atomic number .

Fluorine is the only halogen that does not form compounds with positive oxidation states—i.e., states in which it has lost, rather than gained, electrons. This property is related to fluorine’s having the highest electronegativity of all elements; i.e., it does not give up its electrons to other elements. All halogens possess the oxidation state 0 in their diatomic forms. Fluorine exhibits the oxidation states of −1 (F− ion) and +1 (hypofluorous acid). The principal oxidation states of chlorine, bromine, and iodine are −1, +1, +3, +5, and +7. The oxyacids are compounds in which halogen atoms are joined to oxygen atoms. The oxyacids are all powerful oxidizing agents, which can be reduced to the corresponding hydrogen halides—the oxidation numbers changing from positive to −1 in the process. The oxidizing strength of the oxyanions increases with increasing oxidation number of the halogen atom. All the molecules and ions in which halogen atoms possess four valence electron pairs are tetrahedral, as, for example, in the perchlorate ion (ClO4)−.

Those employing five valence electron pairs, such as chlorine trifluoride (ClF3), have structures derived from a trigonal bipyramidal arrangement of electron pairs. However, since electron lone pairs (i.e., electron pairs that do not bond atoms together) are not located by techniques that analyze structure, only the positions of the fluorine atoms (attached to bonding pairs) are seen. Thus, ClF3 has a T shape resulting from the placement of fluorine atoms at both axial and at one equatorial position of the trigonal bipyramid, with lone electron pairs in the remaining two equatorial positions. Molecules with six valence electron pairs have structures derived from octahedral geometry for the electron pairs; e.g., iodine pentafluoride (IF5) has a square pyramidal structure resulting from the bonding of fluorine atoms by five of the six octahedral electron pairs. The unique binary compound iodine heptafluoride (IF7) has a pentagonal bipyramidal arrangement of fluorine atoms.

Trending Topics Halogenic - definition of halogenic by The Free Dictionary Halogenic - definition of halogenic by The Free Dictionary Related to halogenic: hallucinogenic , Halogen elements hal·o·gen (hăl′ə-jən) n. Any of a group of five chemically related nonmetallic elements including fluorine, chlorine, bromine, iodine, and astatine. adj. 1. Of or relating to the group of elements that are halogens. 2. Of or relating to a bright incandescent light bulb containing a halogen gas that prevents the filament from disintegrating at higher temperatures. [Swedish : halo-, halo- + -gen, -gen.] ha·log′e·nous (hă-lŏj′ə-nəs) adj. halogen (ˈhæləˌdʒɛn) n (Elements & Compounds) any of the chemical elements fluorine, chlorine, bromine, iodine, and astatine.

They are all monovalent and readily form negative ions [C19: from Swedish; see halo-, -gen] ˈhalogenˌoid adj (ˈhæl ə dʒən, -ˌdʒɛn, ˈheɪ lə-) n. any of the electronegative elements, fluorine, chlorine, iodine, bromine, and astatine, that form binary salts by direct union with metals. [1835–45] ha•log•e•nous (hæˈlɒdʒ ə nəs) adj. hal·o·gen (hăl′ə-jən) Any of a group of five nonmetallic elements with similar properties. The halogens are fluorine, chlorine, bromine, iodine, and astatine. Because they are missing an electron from their outermost shell, they react readily with most metals to form salts. The halogens are located in the column of the Periodic Table that is second from the right. See Periodic Table . ThesaurusAntonymsRelated WordsSynonymsLegend: Noun 1.

halogen - any of five related nonmetallic elements (fluorine or chlorine or bromine or iodine or astatine) that are all monovalent and readily form negative ions group , grouping - any number of entities (members) considered as a unit astatine , At , atomic number 85 - a highly unstable radioactive element (the heaviest of the halogen series); a decay product of uranium and thorium atomic number 35 , Br , bromine - a nonmetallic heavy volatile corrosive dark brown liquid element belonging to the halogens; found in sea water atomic number 17 , chlorine , Cl - a common nonmetallic element belonging to the halogens; best known as a heavy yellow irritating toxic gas; used to purify water and as a bleaching agent and disinfectant; occurs naturally only as a salt (as in sea water) atomic number 9 , fluorine , F - a nonmetallic univalent element belonging to the halogens; usually a yellow irritating toxic flammable gas; a powerful oxidizing agent; recovered from fluorite or cryolite or fluorapatite atomic number 53 , I , iodin , iodine - a nonmetallic element belonging to the halogens

; used especially in medicine and photography and in dyes; occurs naturally only in combination in small quantities (as in sea water or rocks) Translations Halogens Halogens Metals & Non-Metals > Halogens The halogens are the salt forming elements placed in Group 17 of the periodic table .

The halogen family elements include elements Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I) and Astatine. These exist in the elemental form as diatomic molecules. The Group 17 gases are also called as halogen gases. Halogens are highly reactive non–metals. At room temperature fluorine and chlorine exist as 'gas'; bromine is liquid and Iodine is a solid. The final member of the group, namely astatine, is intensely radioactive. Its most stable isotope has a half–life of only 8.3 hours. Fluorine is the most electronegative element found in nature. Halogens have a general electronic configuration of ns2np5 ,Thus the addition of only one further electron by either ionic or covalent bonding will confer a noble gas configuration to the halogen atom. They are strong oxidizing agents as they borrow electrons. The most common oxidation state for the group VII elements is −1, although other oxidation states do exist.

They attain noble gas configuration either by gaining one electron to form compounds like NaCl, KI, LiF or by sharing to form a single covalent bond ( HCl, HBr, CCl4, BF3). As the atomic number increases the group VII elements become less reactive. They also become less volatile and darker in color. Fluorine is a pale yellow gas at room temperature, whilst chlorine is a dark greenish yellow. Bromine is a dark red liquid giving off a dense red vapor, whilst iodine is a shiny, greyish black crystalline solid, which can be sublimed to a purple vapor. Physical properties of Group VII elements The decrease in volatility of the elements down the group is the result of increasingly strong van der Waals forces between the molecules as the relative molecular mass increases. These increased intermolecular forces also account for the observed increases in melting points, boiling points and enthalpy changes of vaporization. Because the halogens form simple, non–polar molecules, they dissolve readily in non–polar organic solvents such as tetrachloromethane.

However, chlorine, bromine and iodine are sparingly soluble in water too, although chlorine also undergoes a very slow reaction with the water forming initially chloric acid, HClO(aq), which decomposes to give oxygen and hydrochloric acid: Halogens reacts with metals forns ionic and covalent compounds and with non–metals form covalent compounds. Halogen lamps Uses of halogens In manufacture of halogen lamps. Fluorine as fluoride used in tooth pastes, Chlorine is used to treat waste water and sewage,Bromine compounds play an important role in the manufacture of pharmaceuticals and Iodine has been very useful in treating acne, conjunctivitis, cretinism, vaginitis and ovarian problems. The Halogens - IGGY IGGY Connecting and challenging the world's brightest young minds Username or email Remember me on this device  The Halogens 5/Jun/14 The halogens are 5 chemically related elements that sit just to the left of the noble gases in the periodic table.

Fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At) make up G… This Article Is Only Available To Members 33654_17 - 17 The Halogens: Fluorine, Chlorine, Bromine, Iodine and Astatine 33654_17 33654_17 - 17 The Halogens: Fluorine, Chlorine, Bromine,... SCHOOL View Full Document 17 The Halogens: Fluorine, Chlorine, Bromine, Iodine and Astatine 17.1 The Elements 17.1.1 Introduction Compounds of the halogens have been known from earliest times and the elements have played a particularly important role during the past two hundred years in the development of both experimental and theoretical chemistry.(’) Some of this early history is summarized in Table 17.1. The name “halogen” was introduced by J. S. C.

Schweigger in 1811 to describe the property of chlorine, at that time unique among the elements, of combining directly with metals to give salts (Greek $’As, sea salt, plus the root -YEV, produce). The name has since been extended to cover all five members of Group 17 of the periodic table. Fluorine Fluorine derives its name from the early use of fluorspar (CaF2) as a flux (Latinfluor, flowing). The name was suggested to Sir Humphry Davy by A.-M. Ampkre in 1812. The corrosive nature of hydrofluoric acid and the curious property that fluorspar has of emitting light when heated (“fluorescence”) were discovered in the seventeenth century. However, all attempts to isolate the element either by chemical reactions or by electrolysis were foiled by the extreme reactivity of free fluorine. Success was finally achieved on 26 June 1886 by H.

Moissan who electrolysed a cooled solution of KHF2 in anhydrous liquid HF, using Par electrodes sealed into a platinum U-tube sealed with fluorspar caps: the gas evolved immediately caused crystalline silicon to burst into flames, and Moissan reported the results to the Academy two days later in the following cautious words: “One can indeed make gas; the simplest would be that we are in the ’ M. E. WEEKS, Discovery of the Elements, 6th edn., Journal of Chemical Education, Easton, 1956, Chap. 27, ‘The various hypotheses On the nature Of the liberated halogen family’, pp. 729-77. 789 This preview has intentionally blurred sections. Sign up to view the full version. View Full Document 790 The Halogens: Fluorine, Chlorine, Bromine, Iodine and Astatine Ch.

17 Table 17.1 Early history of the halogens and their compounds -100 -900 - 1200 1529 - 1630 1648 1670 1678 1768 1771 1772 1774 1785 1787 1798 1801 1802 1810 1811 1811 1812 1814 1814 1819 1823 1825 1826 1835 - 1840 1840 1841 1851 1857 1858 1863 1886 1892-5 3000 BC -400 BC -200 -21 AD Archaeological evidence for the use of rock-salt Written records on salt (ascribed to Herodot) Use of salt as part payment for services (salary

) Strabo described dyeworks for obtaining tyrian purple (dibromoindigo) in his Geogruphicu Use of salt to purify noble metals Dilute hvdrochloric acid DreDared bv Arabian alchemist Rhazes DeveloGment of aqua re& ‘(HCl/HNOs) to dissove gold - presumably Clz was also formed Georgius Agricola described use of fluorspar as a flux Chlorine recognized as a gas by Belgian physician J.

B. van Helmont (see Scheele, 1774) Concentrated HCl prepared by J.L. Glauber (by heating hydrated ZnClp and sand) H. Schwanhard (Nurnberg) found that CaFz + strong acid gave acid vapours (HF) that etched glass (used J. S. Elsholtz described emission of bluish-white light when fluorspar was heated. Also described by First chemical study of fluorite undertaken by A. S. Marggraf Crude hydrofluoric acid prepared by C. W. Scheele Gaseous HCI prepared over mercury by J. Priestley C. W. Scheele prepared and studied gaseous chlorine (MnOZ This is the end of the preview. Sign up to access the rest of the document. TERM Previous Page Hydrogen halides, HX 817.2.1 into infinite chains (Fig. 17.3d, e), wher 33654_17a

Question: Which of the Halogens, with the atomic number 17, is missing from - Flourine, Bromine, Iodine and Astatine?
Answer: CHLORINE